Substituted ureas



United States Patent Arln, assignors to Monsanto Chemical Company, St. 7

Louis, Mo., a corporation of Delaware No Drawing. Application December 24, 1956 Serial No. 630,070

8 Claims. (Cl. 260-553) This invention relates to substituted ureas. More specifically, it pertains to an improved process for the preparation of 1,3-diarylureas.

The reaction of carbonyl sulfide (COS) and alkylamines to produce 1,3-dialkylureas in excellent yields is well-known in the art. According to methods heretofore employed, the reaction of arylamines and COS to produce 1,3-diarylamines has been found most unsatis factory requiring exceptionally long reaction periods to produce even small yields of the desired urea.

It is an object of this invention to provide an improved process for the preparation of l,3-diarylureas. It is a further object to provide an improved process for the preparation of 1,3-diarylureas by the reaction of COS and arylamines. Other objects will become apparent from the description of the invention.

It has now been discovered that 1,3-diarylureas can be conveniently prepared in excellent yields by reacting a mono-primary-arylamine and COS in the presence of an alkaline catalyst having a dissociation constant greater than l 10- The following examples illustrate this invention.

Examplel tially evaporated and dilute hydrochloric acid added to precipitate the product. The product, 1,3-diphenylurea (carbanilide), was filtered therefrom and dried. The carbanilide thus obtained had a melting point of 235 C. and represented a yield of 11% on aniline charged.

Example 11 The procedure set forth in Example I was repeated with the exception that 2.0 g. (0.02 mole) of triethylamine was added to the reaction mixture. In this case 15.0 g. of carbanilide was obtained representing a 71% yield based on aniline charged. A comparison of Examples I and II illustrates the advantages of the novel process of this invention.

Example Ill The procedure set forth in Example I is repeated using 214 g. of o-toluidine, 94 g. of COS and 30 ml. of triethylamine. A 45.4% yield of 1,3-bis(2-methylphenyl)-urea, M. P. 263 C., is obtained.

Example IV The procedure set forth in Example I is repeated using 286 g. of fl-naphthylamine, 78 g. of COS and 30 ml. of triethylamine. A 36% yield of 1,3-di-p-naphthylurea is obtained.

. 2 Example V The procedure set forth in Example I is repeated using 18.8 g. of aniline, 28 g. of COS and 6 g. of sodium oleate.

" "An excellent yield of carbanilide is obtained.

Example VI The procedure set forth in Example I is repeated using 18.8 g. of aniline, 28 g. of COS and 3.0 g. of triethanolamine. An excellent yield of carbanilide is obtained.

Example VII The procedure set forth in Example I is repeated using 18.8 g. of aniline, 28 g. of COS and 1.0 g. of KOH. An excellent yield of carbanilide is obtained.

' Example VIII The procedure set forth in Example I is repeated using 25.5 g. of 4-chloroaniline, 28 g. of COS and 2.0 g. of triethylamine. A good yield of 1,3-bis(4-chlorophenyl)- urea is obtained. Comparable results are obtained using 2-chloroaniline and 3-chloronaniline as the starting material.

Example IX The procedure set forth in Example I is repeated using 24.6 g. of 4-methoxyaniline, 28 g. of COS and 2.0 g. of triethylamine. A good yield of 1,3-bis(4-methoxyphenyl)-urea is obtained.

Example X using the indicated aromatic amine:

Aromatic Amine Substituted Ureas ethyl-p-amino-benzoate 1, 3 bis (4 carbethoxyphenyl) urea. p-amlnobenzolc acid 1,3 b1s(4 earboxyphenyl) urea. p amlnobenzonitrile... 1,3 bis(4 eyanophenyl) urea.

1,3 bls(4 methyoxyphenyl) urea. 1,3 b1s(4 methylphenyl) urea. 1,3 bis(2,4 dlmethylphenyhurea. 1,3 bis (2,5 dimethylphenyD-uree.

2,5'dlmethy1an1line 2,6-dimethylanlline 1,3 bis (2,6 dimethylphenyD-urea.

5-chloro-2-methylanillne.... 1,3 bis(5 chloro-2-methyl-phenyl) urea.

5-chloro-2-methoxyanlline 1,3 bis(5-chloro-2-methoxyphenyl) N,N-dlethyl p phenylone-dia- N,N dlmethyl p phenylene-dlamine.

The procedure set forth in the preceding examples is subject to substantial variation without departing from the scope of this invention. Any mono-primary-arylamine can be used in the reaction. By mono-primary-arylamine is meant an arylamine containing only one -N-H group attached directly to an aromatic carbon atom. The aryl radical, of which phenyl and naphthyl are prefe can contain no substituent groups other than cg;

tioned NH group or it may contain one or m substituents which are inert under the conditions" reaction, i. e., do not prevent the formation of any 0 desired 1,3-diarylureas.

3 1o 18 carbon atoms-are preferred. Thermono primary- *ary'lamin'es can be monosubstituted or polysubstituted with one or more of the above mentioned groups. The higher the degree of substitution.the lower the yield of the desired urea. Ortho substituted arylarnines are the Tleast desirable in this re'actionsince'they lower the yield "the desired urea becauseof steric'hindrance. Furthermore, in the case of Z-hydroxy and '2-thio'l substituted arylamines a competing reaction takes place resulting in the formation ofoxazoles and thiazoles in addition to the iformationo'f the desired urea. Thus, in the reaction of {this invention, .2-hydroxyaniline 'will form -some 2-benz- 'oxazo'lol in addition to 'l,3 bis(2 hydroxyphenyl)urea. Similarly, in this reaction, .2-aminothiophenol will form some .Z-benzothiazolol in addition to 1,3-bis (2-mercaptogihenyl'mrea.

'The reaction temperature may also "be substantially varied. Elevated temperatures are used. A temperature of at least 60 C. is preferred and temperatures as high .as .200 C. can be employed. Temperaturesin the range tiffrom about 70 'C. to about 150 C. are particularly preferred.

While the reaction will'take place at atmospheric pressure, elevated pressures are preferred. ,A reaction pres- 'surevarying from about 25 p. 's. i. a. (pounds per square inch absolute) to about 250 p. s. i. a. are particularly advantageous. Reaction presures ashigh as 500 p. s. i. a. or

even highercan be usedif desired butoffer no particular advantage.

The proportions of reactants used in process are also subject to substantial variation. While approximately two molecular proportions of carbonyl sulfidefo'r each molecular proportion of the mono-primary-amine is preferred, the mole ratio ofroarbonyl sulfide to the arozmatic. amine can be varied from about 0.5 :1 :to about 4:1.

vIf desired the process-can be carried out in the presence of an inert solvent or diluent. For this purpose alkyl alcohols containing from 1 to 8 carbon atoms are prestem-ed. Other diluents which can be employed :in this reaction are hydrocarbons, halogenated hydrocarbons, mineral oils, ethers, amines, glycols and acid amides. Water per se is not apreferred diluent although it can be present in minor amounts in the organic diluent. The vfollowing are examples of materials that canb'e employed as ,diluents: ligroin, isopropanol, isopropyl ether, ethanol, tricliloro-et'hylene, pyridine, 'isopropanol-water, ethylene glycol, methyl Cellosolve, tetrahydrofurfuryl alcohol, N,N-dimethylaniline, .N,N-diethyl-ethanolamine, formamide, amyl alcohol, and benzene.

Any alkaline material having a dissociation constant greater than about 1' 1'0- :can be used asthe alkaline catalyst in this reaction. For this purpose tertiary 'alkyl amines containing from 'l to 18 carbon atoms are particularly preferred. Other :catalysts that can be used are quaternary ammonium hydroxides, alkaline earth metal hydroxides, the alkali metal hydroxides, of which sodium hydroxide and potassium hydroxide are particular examples, alkaline alkali metal salts, such as sodium oleate, N,N-dimethylbenzylamine, N,N-diethyl-p-toluidine, tri-nhexylamine, triethanolamine, ,N,N-die.thyloctadecylamine, a mixture of magnesium oxide and methanol, and a mixture of calcium and methanol. The quantity of alkaline material used for the catalyst can also be varied substantially. Minor amounts are preferred. From about 0.002 to about 0.2 mole of the alkaline'catalyst per mole of the aromatic amine havebeen found to be particularly useful.

After the reaction is complete the substituted ureas can be recovered from the reaction mixture by any method .well-knownto those ,skilledin the art.

What is claimedis:

l. In the process for the preparation of substituted ureas by reacting by mixing carbonyl sulfide and amonoprimary-arylamine at a mole ratio of carbonyl sulfide to said amine in the range of from about 0.5:1 to about 4:1 v at an elevated temperature, the improvement which comprises carrying out the reaction in the presence of an alkaline catalyst having a dissociation constant greater than about l 10'- ,2. The process as described in claim 1 wherein the reaction is carried out at a temperature in the range of from about'70" C. to about C.

3. The process as described in claim 2 wherein the alkaline catalyst is aitertiary amine.

4. A process as described in claim 3 wherein the monoprimary-arlyamine is aniline.

5. The process as described in claim 3 wherein the .mono-primary-arylamine is chloroaniline.

6. The process .as described in claim 3 wherein the mono-primary-arylamine is toluidine.

7. The process as described in claim 3 wherein the mono-primary-arylamine is a methoxy substituted aniline.

8. The process as described in claim 3 wherein the mono-primaryarylamine is ,Banaphthylamine.

References Cited in the file of this patent Lewis et al.: J. Am. Chem. Soc., vol. 37 (1915.), page 1977.

Klemenc: Z. Anorg. Ald'gem. Chim., vol. 1 91 (1930), pages 258 and 259.

Uno et al.: C. A., Vol.47, column 386 "(1935). Hagelloch: Berichte Chemische Gesellschaft, vol. (83,

pages 258 to 261 (-1953). 

1. IN THE PROCESS FOR THE PREPARATION OF SUBSTITUTED UREAS BY REACTING BY MIXING CARBONYL SULFIDE AND MONOPRIMARY-ARYLAMINE AT A MOLE RATIO OF CARBONYL SULFIDE TO SAID AMINE IN THE RANGE OF FROM ABOUT 0.5:1 TO ABOUT 4:1 AT AN ELEVATED TEMPERATURE, THE IMPROVEMENT WHICH COMPRISES CARRYING OUT THE REACTION IN THE PRESENCE OF AN ALKALINE CATALYST HAVING A DISSOCIATION CONSTANT GREATER THAN ABOUT 1X10-10.
 2. THE PROCESS AS DESCRIBED IN CLAIM 1 WHEREIN THE REACTION IS CARRIED OUT AT A TEMPERATURE IN THE RANGE OF FROM ABOUT 70* C. TO ABOUT 150* C.
 3. THE PROCESS AS DESCRIBED IN CLAIM 2 WHEREIN THE ALKALINE CATALYST IS A TERTIARY AMINE.
 4. A PROCESS AS DESCRIBED IN CLAIM 3 WHEREIN THE MONOPRIMARY-ARLYAMINE IS ANILINE. 